The Federal Communications Commission (“FCC”) makes various frequency bands available for use by amateur and professional radio operators. Such channels may be simultaneously used by multiple users or user groups, in part due to restrictions on the ranges within which various radio devices may communicate.
For example, Family Radio Service (“FRS”) is one of the Citizens Band Radio Services regulated by the FCC. The FRS is intended for families, friends and associates to use while on a work site, within a neighborhood, on group outings, etc. The FCC has allocated 14 different channels for FRS communications. FRS units may be used without a license, in part because their range is generally less than 1 mile.
Radio devices commonly known as “CB radios,” having a range of 1 to 5 miles, are also regulated by the FCC under the Citizens Band Radio Services. The FCC allows unmodified CB units to be operated without a license.
Users of more powerful radio devices must by licensed by the FCC. For example, users who operate radios in the General Mobile Radio Service bands, having a range from 5 to 25 miles, require a license. Similarly, the FCC issues various levels of amateur or “ham” radio licenses. The level of training needed to obtain each license corresponds with the range of the radio to be licensed. Professional radio operators are subject to yet more rigorous licensing requirements.
Many radio devices use a push-to-talk (“PTT”) circuit for transmitting signals. In order to send a voice transmission with a PTT unit, a user activates a PTT switch (typically by holding down a button) in series with a microphone. The user needs to hold down the PTT switch while speaking. Therefore, these radio units are inconvenient to use in some circumstances, e.g., when a user needs both hands free for other tasks.
Some radios include a voice-operated transmit (“VOX”) circuit which allows a user to transmit a voice signal from the radio device merely by speaking into a radio microphone or the microphone of a headset used with the radio. VOX-enabled radios do not require a switch in series with the microphone, but instead begin to transmit automatically after a voice signal has been received by the microphone. Accordingly, a radio unit having a headset and a VOX circuit may be used in “hands free” mode.
Although radio devices having a headset and a VOX circuit are generally very convenient, they do not perform well in environments having high levels of background noise, such as on a factory floor, or where there is wind noise. In such environments, the radio sometimes will incorrectly interpret the background or wind noise as the user's speech and will start transmitting.
Radio devices having a PTT circuit generally provide better performance in noisy environments because the user may control when transmissions are made. However, even when used with a headset, PTT radio devices cannot provide a hands free mode of use.
Previously, if a user had wished to use a headset and change between VOX and PTT operation of a VOX-enabled radio unit, a user would have needed to carry a VOX headset and a PTT headset. A user may have known that she would be working in an environment which would be noisy some of the time, or may have known that she would be working outdoors where it may be windy. Carrying two headsets was inconvenient, but choosing one or the other would result in sub-optimal performance for changing conditions.